title: Intrinsic determinants of optic nerve regeneration.
abstract: OBJECTIVE
  To review the functions of these intracellular signals in their regulation of retinal ganglion cell (RGC) axon regeneration.
  
  
  METHODS
  Relevant articles published in English or Chinese from 1970 to present were selected from PubMed. Searches were made using the terms "intrinsic determinants, axon regeneration, RGC, optic nerve regeneration, and central nervous system axon regeneration."
  
  
  METHODS
  Articles studying the mechanisms controlling RGC and central nervous system (CNS) axon regeneration were reviewed. Articles focusing on the intrinsic determinants of axon regeneration were selected.
  
  
  RESULTS
  Like other CNS neurons of mammals, RGCs undergo a developmental loss in their ability to grow axons as they mature, which is a critical contributing factor to the failure of nerve regeneration and repair after injury. This growth failure can be attributed, at least in part, by the induction of molecular programs preventing cellular overgrowth and termination of axonal growth upon maturation. Key intracellular signals and transcription factors, including B cell lymphoma/leukemia 2, cyclic adenine monophosphate, mammalian target of rapamycin, and Krüppel-like transcription factors, have been identified to play central roles in this process.
  
  
  CONCLUSIONS
  Intense effort and substantial progress have been made to identify the various intrinsic growth pathways that regulate RGC axon regeneration. More work is needed to elucidate the mechanisms of and the interrelationship between the actions of these factors and to successfully achieve regeneration and repair of the severed RGC axons.
authors.affiliation: Department of Ophthalmology, Peking University First Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100034, China.
authors.forename: Rui-lin
authors.initials: RL
authors.lastname: Zhu
authors.forename: Kin-sang
authors.initials: KS
authors.lastname: Cho
authors.forename: Chen-ying
authors.initials: CY
authors.lastname: Guo
authors.forename: Justin
authors.initials: J
authors.lastname: Chew
authors.forename: Dong-feng
authors.initials: DF
authors.lastname: Chen
authors.forename: Liu
authors.initials: L
authors.lastname: Yang
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000502:physiology; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000502:physiology; D009416:Nerve Regeneration; D009900:Optic Nerve / Q000502:physiology*; D051059:PTEN Phosphohydrolase / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000502:physiology; D058570:TOR Serine-Threonine Kinases / Q000502:physiology
chemical_list: D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D019253:Proto-Oncogene Proteins c-bcl-2; C106644:SOCS3 protein, human; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D000242:Cyclic AMP; D058570:TOR Serine-Threonine Kinases; D051059:PTEN Phosphohydrolase